Error 1200 indicates that the Cloudflare edge server has reached its limit for concurrent connections queued for a particular origin or cache resource. This typically happens when the origin server is very slow to respond, causing connections to pile up at the Cloudflare edge. As more visitors arrive while previous requests are still waiting, the queue fills up and Cloudflare starts returning 1200 to shed load. It is a sign that the origin is a bottleneck.
The origin is taking a long time to respond to each request, causing Cloudflare to hold many open connections simultaneously until the per-host connection limit is reached.
A sudden increase in traffic generates more concurrent requests than the origin can handle, causing a backlog at the Cloudflare edge.
Many requests for uncached content hit the origin simultaneously (e.g., after a cache purge or for dynamic content), overwhelming the origin connection pool.
Monitor your origin server's response times, CPU, memory, and connection counts. Identify and fix whatever is making it slow.
top -bn1 | head -10 && ss -s
Configure Cloudflare to cache more content with longer TTLs. This reduces the number of requests that need to reach the origin.
If the origin is genuinely overwhelmed, scale it vertically (more resources) or horizontally (more servers behind a load balancer).
Enable features like Always Online (serves stale cache if origin is down), Tiered Cache (reduces origin connections), or Argo Smart Routing (optimizes path to origin).
Cloudflare connected to the origin but the origin did not respond with an HTTP response in time.
Cloudflare's TCP connection to the origin server timed out.
Cloudflare received an empty, unknown, or unexpected response from the origin server.